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Published on: October 21, 2011
Diazinon oxon affects the differentiation of mouse N2a neuroblastoma cells
Erasmia Sidiropoulou1, Magdalini Sachana, John Flaskos
1Department of Veterinary Pathology, Faculty of Veterinary Science, University of Liverpool, Leahurst CH647TE, UK.
Abstract:
The aim of this study was to assess the neurotoxicity of diazinon oxon (DZO), a major in vivo metabolite of the phosphorothionate insecticide diazinon (DZ), on differentiating mouse N2a neuroblastoma cells. When used at concentrations of 1, 5 and 10 microM, DZO did not cause cell death but it impaired the outgrowth of axon-like processes after 24 h. Densitometric scanning of Western blots of lysates of N2a cells revealed that exposure to 5 or 10 microM DZO for 24 h increased the expression of phosphorylated neurofilament heavy chain (NFH) compared to controls, while there was no significant change in total NFH. By contrast, treatment of N2a cells with 1-10 microM DZO resulted in marked reductions in the expression of the axon growth-associated protein GAP-43. DZO-treated cells also showed an increased expression of the heat shock protein HSP-70 compared to controls. The above biochemical changes were not temporally related to inhibition of acetylcholinesterase (AChE). These data suggest that biologically relevant, subcytotoxic levels of DZO may exert neurotoxic effects on differentiating cells and that the mechanisms involved are different from those attributed to its parent compound.
Insights
Diazinon oxon (DZO), a metabolite of the insecticide diazinon, impairs nerve cell growth and alters key protein expressions at non-lethal levels. These neurotoxic effects occur through mechanisms distinct from its parent compound.
Area of Science:
- Neuroscience
- Toxicology
- Cell Biology
Background:
- Diazinon (DZ) is a widely used organophosphate insecticide.
- Diazinon oxon (DZO) is a primary in vivo metabolite of diazinon.
- Understanding the neurotoxic potential of DZO is crucial for risk assessment.
Purpose of the Study:
- To investigate the neurotoxic effects of DZO on differentiating mouse N2a neuroblastoma cells.
- To identify specific molecular changes induced by DZO exposure.
- To differentiate DZO's neurotoxic mechanisms from those of its parent compound, diazinon.
Main Methods:
- Exposure of differentiating mouse N2a neuroblastoma cells to varying concentrations of DZO (1, 5, 10 microM).
- Assessment of cell viability and axon-like process outgrowth.
- Western blot analysis to quantify protein expression levels (phosphorylated and total NFH, GAP-43, HSP-70).
- Measurement of acetylcholinesterase (AChE) activity.
Main Results:
- DZO did not induce cell death but inhibited axon-like process outgrowth at 1-10 microM.
- Increased expression of phosphorylated neurofilament heavy chain (NFH) and heat shock protein HSP-70 observed.
- Marked reduction in the expression of growth-associated protein GAP-43.
- Biochemical changes were not correlated with acetylcholinesterase inhibition.
Conclusions:
- Sub-cytotoxic levels of DZO exhibit neurotoxic effects on differentiating neuronal cells.
- DZO-induced neurotoxicity involves alterations in NFH, GAP-43, and HSP-70 expression.
- The mechanisms of DZO neurotoxicity differ from those of the parent compound, diazinon.
